1. Field of the Invention
This invention relates generally to coatings deposited on transparent articles and, more particularly, to novel methods for restoring or repairing coatings deposited on transparent substrates which have been damaged by scratches, abrasive rubs or the like.
2. Description of the Prior Art
Because of the increasing costs of and the inadequate supplies of available energy, the number of reflective windows employed for conserving energy, particularly in commercial buildings, is increasing. Heretofore, when the coating of a reflective window was damaged, the window was replaced because of the difficulty of restoring the damaged area of the film to its original light transmittance condition. However, the increased cost of reflective windows and the number of such windows in use today makes the replacement of such windows uneconomical. Thus, it is now desirable to develop a method or system for repairing the damages to the coating of a reflective window whereby the light transmittance characteristics of the repaired area is substantially the same as that of the original coating so that it will not be necessary to install a costly new reflective window.
As previously mentioned, a reflective window generally comprises a glass substrate on which a thin transparent film of a metal, metal halide, metal oxide or mixtures or stacks thereof is deposited to reflect a large portion of the solar rays incident thereon and control the transmittance of light therethrough. One type of a commercially available reflective window comprises a heat reflecting chromium based film deposited on the inboard surface of a glass substrate to provide a filmed glass of controlled daylight transmittance in the range of between about 8% to 50%. Such a filmed window will exhibit some reflected color but is substantially neutral in transmittance. As is well known, the transmittance of light through clear glass is over 90%. Thus, when damages such as scratches, abrasive rubs, pin holes or the like occur in the metallic film, the damage is very noticeable because of the great difference of the light transmittance between an intact film area and a damaged film area. Although the metallic film is quite durable, care must be taken to prevent damage thereto during handling and installation. However, due to the complexities and hazards inherent in glazing reflecting windows in buildings, some damage to the film may occur.